How Coral Movement Reveals Your Flow Problems (And How to Fix Them

The Tank Whisperer Series #2: Coral Movement and Water Flow

Corals may not speak, but their movement speaks volumes. One of the most overlooked aspects of reef tank success is proper water flow — and if your coral could talk, they’d be shouting about it.

Water flow is how your coral breathes, eats, removes waste, and maintains its tissue health. But not all corals want the same type of flow. Too strong, and they retract. Too weak, and they slime up or collect detritus.

Here’s how to read what your tank is telling you:

Flow Preferences by Coral Type

Soft Corals (Zoanthids, Mushrooms, Leathers):

• Prefer gentle, indirect flow

• Movement should look relaxed and swaying

• If they fold, blow sideways, or stay closed — it’s too much

LPS Corals (Hammers, Torches, Frogspawn):

• Prefer moderate, pulsing flow

• You want a rhythmic, back-and-forth motion

• If tentacles overextend or flesh tears, dial it back

SPS Corals (Acropora, Montipora):

• Need strong, turbulent flow

• Aim for random, chaotic movement to keep surfaces clean

• Laminar or one-directional flow can lead to tissue recession

Signs You Have a Flow Problem

• Polyps retract or don’t extend: Too strong or too direct flow

• Tissue recession: Possibly from powerhead blasts

• Detritus collecting on or around coral: Flow is too weak

• Slimy film on coral: Often from dead spots or poor waste removal

Fixes That Work

• Use random flow modes on your wavemakers

• Rotate pump angles slightly every few weeks

• Use gyre-style pumps for wide, gentle circulation

• Don’t forget feeding mode when target feeding LPS corals

Final Thought

Every coral is different, and your job as a reefer is to observe and adjust. Watch your tank after every new placement or pump tweak. Let your coral behaviour guide you — because they’re already telling you what they need.

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